The violence in Osh has once again put the focus on the Ferghana Valley as one of the potentially most explosive regions of the former Soviet Union. What makes it that way?

The home of cities like Osh and Andijon, the Ferghana Valley is the most densely populated area of Central Asia and the most explosive.

More than 10 million people live in the valley, which covers some 22,000 square kilometers -- comparable in size to Kashmir or the Nile Delta.

For millennia, it has been Central Asia's breadbasket, an expanse of river-fed green fields standing out in stark contrast to the dry mountains and plains typical of the region.

But today, far from being an idyllic place, it has become best known for epic-scale violence.

This month's deadly interethnic clashes that have forced an estimated 400,000 Uzbeks and Kyrgyz from their homes in southern Kyrgyzstan is just the most recent example.

In 2005, Uzbek forces opened fire on Uzbek protestors in Andijon, the country's fourth-largest city, killing from several hundred to 1,000 people according to differing estimates.

In 1999, hundreds of Islamic Movement of Uzbekistan guerrillas seized villages in Kyrgyzstan to launch attacks into Uzbekistan before being counterattacked by Kyrgyz forces backed by Uzbek and Kazakh aircraft.

Ethnic Jigsaw

Why is the Ferghana Valley, which is divided in three irregular, jig-saw pieces between Uzbekistan, Kyrgyzstan, and Tajikistan such a hot-spot for violence of all kinds?

Part of the reason is precisely that division, which Josef Stalin ordered in the 1930s. The map-making gave each republic an expanse of fertile land but ignored the fact that much of the valley was a patchwork of ethnicities not easily incorporated into national republics.

The tensions began to surface with the break-up of the Soviet Union and two of its consequences.

One was that all three newly independent republics began stressing their national identities despite having multiethnic enclaves.

The other was that living conditions across the valley plummeted as its agricultural system based on collective farms collapsed, setting off a new competition for livelihoods and resources.

John MacLeod, a Central Asian expert at the London-based Institute for War and Peace Reporting (IWPR) says, "The collective farm was by no means an efficient system, the Soviet system of having large village-sized farms as economic units, but when that was effectively broken up by policy or just by default as things fell apart after the end of the Soviet Union, the farming didn't become more efficient."

"Of course some successful farmers emerged, but the others just didn't have enough land to make a viable living or have their own tractor or their own means to buy seed," MacLeod says.

MacLeod says that in southern Kyrgyzstan this economic dislocation forced many Kyrgyz, who were traditionally farmers and nomads, into cities to look for work. But the economic life of the cities is dominated by Uzbeks, who traditionally were the valley's merchants.

"Over the decades and particularly, perhaps, since Kyrgyzstan became an independent state, there has been an urbanization of the ethnic Kyrgyz rural population," MacLeod says.

"So, you have a recently rural Kyrgyz population moving into the towns and clearly that creates a competition for urban resources, for employment, for space at the open-air market, for running small businesses, all that kind of thing."

Recently, that competition has only sharpened as the global economic downturn has narrowed the impoverished Ferghana Valley's pressure valve: outmigration of labor. In past years, thousands of valley residents have gone to Russia and Kazakhstan to work as laborers and send back remittances. Now, those opportunities have shrunk and so have the remittances many families depend upon to stay afloat.

The fact that Osh exploded this month, at a time when there is only weak central rule Kyrgyzstan, may be a telling measure of the pent-up socioeconomic pressures.

Matthew Clements, Eurasia Analyst at the Country Risk department of IHS Jane's in London, notes that much the same happened the last time central rule dramatically weakened in Kyrgyzstan. That was in 1990, a year before the Soviet Union dissolved.

Ferghana Valley is deeply religious

"In the period of uncertainty around the collapse of the Soviet Union there was a period of government weakness there, when there was little government oversight and control of the region and these tensions were allowed to become exacerbated and to escalate in the way they did," Clements says.

"And similarly, in this situation we have now -- whereby [Kyrgyzstan's interim] government has been unable to establish its authority over certain areas of the country -- it created a situation whereby there was no possibility of nipping it in the bud when these small-scale clashes broke out on the June 10."

In the Kyrgyz-Uzbek rioting that engulfed Osh in 1990, some 300 people died.

Antigovernment Sentiment

Clements notes that the other two Central Asian countries with a piece of the valley also face pent-up pressures, though the nature of their valley populations and how they deal with them varies.

Highly authoritarian Uzbekistan maintains a massive security presence in its part of the valley to keep the lid on discontent among the overwhelmingly Uzbek inhabitants. Tashkent keeps the minority populations of Kyrgyz and Tajiks that also share the land equally tightly controlled.

By contrast, Clements says, Tajikistan deals with the pressure in its part of the valley, which is mostly inhabited by Uzbeks, by largely staying out of its affairs.

"Tajikistan is a different issue altogether and part of the issue there is that there is very little government control outside of Dushanbe. And due to the geographical nature as well, the Ferghana Valley region of Tajikistan, where many of the Uzbeks do reside, is quite literally cut off from the rest of the country by the mountain ranges," Clements says.

"And I think in some ways this has kind of reduced the Tajik influence in the region and it does kind of prevent in a way some of these tensions from developing."

Nevertheless, all three parts of the Ferghana Valley pose clear dangers for their respective states. Each is poor, has a dangerous current of antigovernment sentiment, is susceptible to radical Islamic movements, and -- as part of the drug-trafficking route from Afghanistan -- has a significant organized crime presence. And that is without even mentioning the intercommunal tensions now so evident in southern Kyrgyzstan.

Faced with such a tinderbox, the governments of Uzbekistan, Kyrgyzstan, and Tajikistan appear to have developed at least one common understanding, despite their frequent fights over water and energy and other issues; that is, to keep the lid on the box by cooperating in suppressing radicalism but staying out of each others' internal crises, even when their own ethnic kinsmen are endangered.

Dilip Hiro, author of the book "Inside Central Asia," says it is unlikely the current crisis will see Uzbekistan try to safeguard the Uzbek community across the border by moving its own forces into the security vacuum there.

Hiro says these operating rules were underlined when the Collective Security Treaty Organization (CSTO) formulated a response to the crisis earlier this week (June 14).

"The Russian president's statement itself said that if necessary we will send peacekeepers from the CSTO, which has seven countries including Uzbekistan. But they will not go as individual countries on their own," Hiro says.

The CSTO groups all the Central Asia countries, except Turkmenistan, with Russia, Belarus, and Armenia.

The group said it will furnish trucks, helicopters, and fuel to Bishkek to transport Kyrgyz forces to the south of the country. But it made it clear that sending peacekeepers -- an act that would only underline Bishkek's own weakness further -- would be the last resort.